Pneumatically-operating musical instrument



ma. 3. 192s.

M. A. BALTHASR y PNEUIATICALLY'OPERATING MUSICAL INSTRUMENT Filed June 5, 19;;2 2 Shouts-Sheet l M. A. BALTHASAR PNEUIATICALLY OPERATING MUSICAL INSTRUMENT Feb. 3. 1925.

Filed Jun s, 1922 2 Shun-Sheet z Fig@ Patented Feb. 3, 1925.

UNITED STATES MARIE AMLIE BALTHASAR, 0F NAMUR, BELGIUM.

PNEUMATICALLY-OPERATING MUSICAL INSTRUMENT.

Application led June 3, 1922. Serial No. 565,612.

To all w 710m t may concern Be it known that I, Manin AMLIE BAL- 'rinisein Isubject of the King of Belgium, and resident of Namur, Belgium, have invented certain new and useful Improvements in Pneumatically-Operating Musical Instruments, of which the following is a specification.

This invention relates to pneumatically operating musical instruments with deadened vibrations. Y

In instruments of this type, the hammers adapted to strike the strings or other sound generators are actuated by bellows, the inner chamber of which can be connected either with the atmosphere, or with a pipe line in which exists a reduced pressure. In the first case, the bellows remains stationary, in the second case, the bellows is actuated and the string corresponding to this bellows is caused' to vibrate.

The primary control member of the pipe line leading to the bellows is a perforated paper strip which unwinds in front of the orifices of the pipe lines, for obturating them or connecting` them with the atmosphere. As the pipe lines have a branch of small dian'ieter connected to the reduced pressure chamber, it will be seen that when the orifice of a pipe line is closed by the paper strip, a reduced pressure is determined in this pipe line, and on the contrary, when the pipe line is opened, it is immediately brought back to atmospheric pressure.

It will be understood .that it is impossible to directly control the bellows by the perforated paper strip, as the perforations would be too long, the notes being at rest when their bellows communicate with the atmosphere.

Reversing relays are therefor used, which allow the bellows to communicate kwith the atmosphere when the orifices controlled by the paper strip are-closed.

These relays are each constituted by a. valve moving between two seats, one of which opens to the atmosphere the other to the reduced pressure chamber, and which controls the pipe line of the bellows. 'Ihe valve which when at rest connects the bellows with the atmosphere, lis actuated by a resilient diaphragm, on one of the faces of which permanently acts the reduced pressure and which closes, by its other face, a

chamber connected with the atmosphere byV a pipe line controlled by the perforated paper strip. v'Ihis chamber is, moreover, perforated with a hole of small diameter which connects it to the pipe line in which exists a reduced pressure.

It will be understood that the valve is actuated and consequently the bellows correspondinn thereto, only when ahole is presented in front of the orifice controlled by the paper strip.

The conditions for the proper operation of the said reversing relays are the following:

lo-The valve, when it is actuated, must immediately leave the seat on which it rests (seat open to the reduced pressure).

QO--It must pass from one seat to the other, with the maximum possiblespeed.

30e-Uien the diaphragm ceases to act, the valve also must in'imediately come back to rest.

The invention has essentially for its purpose to realize these conditions. It is also adapted to permit the ready adjustment of the distance between the two valve seats and, also, to allow the adjustment of the distence separating the resilient diaphragm and the valve, without necessitating taking the relay to pieces. i

The invention is described hereinafter with reference to the accompanying drawing which diagrammatically'illustrates, by way ofexample, a form of construction.

Fig. l. is a partial sectional elevation. "Fig: 2 is a view similar to Fig. 1, the valve being in a different position'.

Fig. Bis a plan view.`

Fig. 4 is a sectional view on line A-A of Fig. 2. i

In this example, l designates a striker arm, and 2 a movable wall Aof a bellows, the inner chamber 3 of which is connected by the pipe tto the chamber 5 having two valve seats, one of which 6, opens to the atmosphere, and the other of which, 7, in the chamber 8 is tubular, and is connected the pipe 9 to a reduced pressure generator. The valve l0 can seat on one or the'other of ythe seats, and when at rest, it lits on'the seat T. Its pilot ll, guided by tubular seat 7, rests on the resilient diaphragm l2 closing the box 13 perforated with a small hole 14 and connected to the pipe l5 controlled by the perforated paper strip 16. i i

Further, the chambers 5 and S are formed by two metallic boxes l? and 18 assembled in a fluid-tight manner on the intermediate metallic partition 19. Moreover, the seat 7 is constituted by a cylindrical tube capable of frictionally Ysliding in a corresponding orifice of the partition 19, andthe strolreof the valve 10 can therefore be modified by means of the sliding movement of the'tube 7.

Besides the pilot 11, which has a polygonal cross section (square cross section in the example illustrated,) is guided in the tube F. Consequently, when the valve is moved away from its seat F, a communication is established between the chambers 8 and 5 (Figure 3) through the space existing between the' polygonal periphery of the pilot 11 and the inner cylindrical surface of the tube F.

Also, the box 13 carries a branch 20 capable of frictionallyfsliding in the tube 21 integral with the box 18, which branch extends to the exterior of the box 18.

By acting on the branch 20, the box 13 vcan therefore be moved towards or from the pilot 11 without removing the element.

Y The operation is as follows:

The valve 10 is supposed to rest initially on the seat 7 and the pipe 15 Vto be closed by the perforated paper strip 16.

Phase 1.-Tlie valve 10 resting on the seat 7, the bellows 3 communicates with the atmosphere and the parts occupy the position illustrated in Fig. 1.

A partial vacuum exists in both the chambers 8 and 13, owing to the blow-through hole 14 (called capillary hole because of its small diameter) and for the reason that the pipe 15 is obturated by the perforated paper strip 16.

Phase 2.A hole of the perforated paper strip 16 comes in coincidence with the orifice of the pipe 15. The air then enters in this pipe and produces the following results:

1Owing to its speed and by reason of its kinetic energy (living force) the quantity of air introduced lifts the diaphragm g 12 and consequently produces the immediate unloosening of the valve 10 from its seat.

2O-The chamber 13 comes under a pressure close to that of atmospheric pressure and in any case greater than the pressure existing in 8. Consequently, the diaphragm 12 continues its action on the pilot 11, of the valve 10 until the latter rests on the seat6.

In consequence, the bellows 3 is put into communication with a partial vacuum, and the movable partition 2 folds back on the fixed partition, drawing along the striker` arm 1.

Phase 3.-The perforated paper strip again obturates the pipe 15. Owing to the' hole 14 a partial vacuum is created in the chamber 13 and the diaphragm 12 becomes inert. In consequence, Y pressure which is exerted on the upper face of the valve 10 determines the displacement thus giving the atmospheric of this valve which closes on the seat 7.

The bellows 3 is again connected with the v Yair suiiices to produce the loosening of the valve from its lower seat 7 which would take place even if there was no difference between the surface of the diaphragm 12 and that of the seat 7.

Condition Il-On the other hand, if S12 is the surface of the diaphragm 12, s the surface of the seat 6, H the atmospheric pressure', 7L the pressure in the vacuum pipe line.V then the force which tends to apply the valve to the seat 6 is, (H-L) (S12-SG). lt is therefore obvious that S12 must be as great and s as small as possible, without however the outflow of the seat 6 being diminished.

For this reason, the seat 6 is composed of several holes surrounded by conduits turned towards the valve 10, as clearly illustrated in the drawing. rThe out-fiow Ycan thus be maintained equal to, or greater than, the outflow of the single hole generally used in apparatuses of this kind, and the total surface ofthe multiple holes is less than that of the single hole. In fact, the outiiow depends on the perimeter of the openings, admitting that the lift of the valve and the value of the partial vacuum remain constant. Now

holes, in case they are five in number, as in the example illustrated, is equal to 10m, rrA

being the radius of each 0f the holes. The

.perimeter of the single hole having R for radius and giving the same outflow as the multiple holes would be.

Y F 5 lt is thenseen that the total surface ofV the multiple holes is:

..-naar 7F 25 5 that is to say the ifthof the surface of the for permitting the outflow of multiple holes, and the existence of conduits increases the height of t-his section of passage of the air, which allows placing the holes nearer together and, consequently, diminishing the space occupied.

Condition III-The force which produces the return of the valve is obviously so much the greater according as the surface Subjected to the partial vacuum is also greater. It is for that reason that the seat 7 is a seat having a single hole, and consequently presenting a large surface. Apparat-uses already exist in which the seat opening to the atmosphere has a large outflow and a small surface, but the seat opening to the partial vacuum also has a. large outflow and a small surface, so that this condition III is not realized in the said apparatuses.

T he invention is characterized on the contrary by the combination of an upper seat having multiple holes and flanged edges (consequently having a small surface although a large outflow), with a lower seat having a single hole (consequently having a large surface).

What I claim as my invention and desire to secure by Letters Patent is:

l. In a pneumatically operating musical instrument, a metal plate forming a valve seat, a plurality of apertures, with flanged edges provided on the said seat, a valve, a valve stem, a tube forming a guide from the said stem and forming at the same time a second valve seat having a single aperture, a plate for supporting the said tube, means for moving the tube relatively to the said plate, a diaphragm acting on the valve stem, a diaphragm chamber, an axial tube forming an extension of the said chamber, and means for supporting the axial tube.

2. In a pneumatically operating musical instrument, a metal plate forming a valve seat, a plurality of apertures with flanged edges provided on the said seat, a valve, a valve stem, a tube forming a guide for the said stem and forming at the same time a second Valve seat having a single aperture, a plate for supporting the said tube, means for moving the tube relatively to the said plate, a diaphragm acting on the valve stem, a diaphragm chamber, an axial tube forming an extension of the said chamber, a plate for supporting the axial tube, and means for moving the latter relatively to this plate.

3. In a pneumatically operating musical instrument, a casing, a plurality of apertures with flanged edges provided in the bottom of this casing, a second casing fitting the first one, a central aperture in this second casing, a valve, a valve stein, a tube forming a. guide for the said stem and forming at the same time a second valve seat having a single opening, the valve stem passing through the said single opening, a third casing covering the second one, an aperture in this third casing, a diaphragm, a diaphragm chamber, a tube forming an extension of this chamber and passing through the aperture provided at this chamber and passing through the aperture provided at the bottom of the third casing, a side pipe entering the first casing, and a side pipe entering the third casing.

Signed at Brussels, Belgium, this twentysecond day of May A. D. 1922.

MARIE AMELIE BALTHASAR. 

